Functions of Arabidopsis C-terminal Domain Phosphatase-like 4 in Global Transcriptional Regulation

Phosphoregulation of the carboxyl-terminal domain of RNA polymerase II largest subunit (pol II-CTD) couples transcription and co-transcriptional modification of nascent RNA. Although the molecular mechanisms have been extensively studied in vertebrates, understanding of that in plants is still in its infancy. Through genetics, biochemical and transcriptomic approaches, this dissertation work characterizes functions of a pol II-CTD phosphatase-like protein from Arabidopsis thaliana, CPL4, in the phosphoregulation of pol II-CTD during protein-coding and non-coding RNA transcriptions. CPL4 interacts with and dephosphorylates pol II-CTD both in vitro and in vivo, showing that CPL4 regulates pol II-CTD phosphorylation status in Arabidopsis. An amino acid substitution in the catalytic motif abolished the phosphatase activity of CPL4. The catalytically inactive protein strongly inhibits transcription in transient assays, likely due to a dominant negative effect. Deletion of Breast cancer C-terminal (BRCT) domain alleviates the inhibitory effect of the catalytically inactive CPL4, suggesting that BRCT domain is necessary for CPL4’s function. A suite of xenobiotic stress responsive genes shows constitutive up-regulation in CPL4 knockdown transgenic (CPL4RNAi) lines, indicating that CPL4 negatively regulates the toxic chemical detoxification pathway. The CPL4RNAi plants accumulate aberrant 3’-extended transcripts from many pol II-dependent small nuclear RNA (snRNA) loci. The snRNA 3’-extension gives rise to a snRNA transcript fused with a downstream protein-coding gene (DPG) if present. Such snRNA-DPG fusion transcripts can be found in other plant species. A short, unstable non-coding RNA produced from a protein-coding locus driven by a transposable-embedded snRNA promoter can yield the full-length product in the CPL4RNAi plants. These snRNA-DPGs can be induced in wild type by salt stress, which affects pol II-CTD phosphorylation status. These results indicate a potential stress-inducible conversion of non-coding RNA transcription into protein-coding transcription mediated by pol II-CTD phosphoregulation. CPL4RNAi root explants exhibit enhanced capability of de novo shoot organogenesis due to cytokinin hypersensitivity and earlier induction of shoot apical meristem regulatory genes. A potential involvement of an operon-like cluster of thalianol biosynthesis genes in the CPL4RNAi organogenesis phenotype is implicated. Taken together, Arabidopsis CPL4 is an essential pol II-CTD phosphatase, regulating stress-responsive and organogenesis pathways through protein-coding and non-coding RNA transcriptions

W205-Controlling Winter Annual Broadleaf Weeds

Maintaining a vigorous turfgrass stand will protect against weed infestation. However, during the winter months turfgrasses are not actively growing and are therefore susceptible to the encroachment of winter annual broadleaf weeds. Controlling winter annual broadleaf weeds before they are able to set seed will not only reduce the likelihood of an outbreak the following year, but improve the aesthetic quality of the turfgrass stand

Use of Acetolactate Synthase-Inhibiting Herbicides in Inzen Grain Sorghum (Sorghum bicolor L. Moench ssp. bicolor)

Grain sorghum is typically grown as a rotational crop in Arkansas because of its many benefits, one being the effective control of Palmer amaranth through the use of atrazine. However, limited options exist for postemergence (POST) control of weedy grasses within the crop. Inzen™ grain sorghum is the result of a nicosulfuron resistant weedy sorghum biotype cross-bred with a commercial line of grain sorghum. Inzen™ allows for safe use of over-the-top applications of nicosulfuron within the crop. Nicosulfuron is an acetolactate synthase (ALS)-inhibiting herbicide, which has historically been used in corn for control of weedy grasses. Experiments were conducted in 2016 and 2017 to (1) evaluate the tolerance of Inzen™ grain sorghum to various herbicides in Weed Science Society of America Group 2 ALS-inhibiting herbicides, (2) evaluate weed control programs utilizing nicosulfuron, and (3) determine the sensitivity of conventional grain sorghum to low rates of nicosulfuron and glufosinate. Results indicate Inzen™ grain sorghum was tolerant to ALS-inhibiting herbicides evaluated when applied directly to the soil prior to crop emergence (PRE). When ALS-inhibiting herbicides were applied to Inzen™ grain sorghum at the V4 growth stage, a high level of resistance was observed to all herbicides, with the exception of bispyribac-Na, which resulted in 20% visible injury and a 35% yield reduction. Additionally, weed control programs utilizing S-metolachlor preemergence and nicosulfuron + atrazine applied POST resulted in a yield increase along with acceptable control of both Palmer amaranth and johnsongrass. Finally, conventional grain sorghum appeared to be most sensitive to low rates of nicosulfuron and glufosinate at V8, flagleaf, or heading growth stages. Yield reductions of up to 96% were observed from rates of nicosulfuron equivalent to 1/10X of a labeled use rate. Nomenclature: Inzen; atrazine; byspyribac; glufosinate; nicosulfuron; S-metolachlor; johnsongrass, Sorghum halepense L. Pers.; Palmer amaranth, Amaranthus palmeri S. Wats.; corn, Zea mays L.; grain sorghum, Sorghum bicolor L. Moench ssp. bicolo

Efeitos competitivos da mistura de stands de trigo e biotipos de kochia (Kochia scoparia) resistentes e susceptíveis aos herbicidas inibidores da acetolactase sintase

Greenhouse experiments were conducted to compare the competitive ability of sulfonylurea resistant and susceptible kochia (Kochia scoparia L. Schard) compared to wheat. The results of several replacement series experiments indicate that wheat was the dominant competitor, and an average of one wheat plant reduced resistant kochia yield per plant equal to the effect of 4.8 resistant kochia or 5.4 susceptible kochia plants. Intraspeciflc competition was more important than interspecific competition for wheat, whereas the reverse was true for the resistant and susceptible kochia. The results of the niche differentiation index (NDI) indicate that wheat and either resistant or susceptible kochia are only partly limited by the same resources. The resistant and susceptible kochia, however, are limited by the same resources.Experimentos foram instalados em condições de casa-de-vegetação com o objetivo de comparar a capacidade competitiva de biotipos resistentes e suscetíveis aos herbicidas inibidores da enzima acetolactase synthase da planta daninha kochia (Kochia scoparia L. Schard) comparada com trigo. Os resultados de diversos experimentos, utilizando a metodologia chamada de substitutiva, indicaram que o trigo foi o competidor dominante, e em média uma planta de trigo reduziu o crescimento da planta de kochia resistente igual ao efeito de 4,8 plantas de kochia resistente ou 5,4 plantas de kochia suscetível. A competição chamada de intraespecífíca foi mais importante que a competição interespecífica para o trigo, porém o inverso foi verdadeiro para os biotípos resistentes e susceptíveis de kochia. Os resultados do índice de diferenciação ecológica indicaram que trigo e qualquer um dos dois biotípos de kochia estudados foram limitados apenas parcialmente pelos mesmos recursos de crescimento. No entanto, o crescimento dos biotípos resistentes e susceptíveis de kochia foram limitados pelos mesmos fatores de crescimento

Functions of Arabidopsis C-terminal Domain Phosphatase-like 4 in Global Transcriptional Regulation

Phosphoregulation of the carboxyl-terminal domain of RNA polymerase II largest subunit (pol II-CTD) couples transcription and co-transcriptional modification of nascent RNA. Although the molecular mechanisms have been extensively studied in vertebrates, understanding of that in plants is still in its infancy. Through genetics, biochemical and transcriptomic approaches, this dissertation work characterizes functions of a pol II-CTD phosphatase-like protein from Arabidopsis thaliana, CPL4, in the phosphoregulation of pol II-CTD during protein-coding and non-coding RNA transcriptions. CPL4 interacts with and dephosphorylates pol II-CTD both in vitro and in vivo, showing that CPL4 regulates pol II-CTD phosphorylation status in Arabidopsis. An amino acid substitution in the catalytic motif abolished the phosphatase activity of CPL4. The catalytically inactive protein strongly inhibits transcription in transient assays, likely due to a dominant negative effect. Deletion of Breast cancer C-terminal (BRCT) domain alleviates the inhibitory effect of the catalytically inactive CPL4, suggesting that BRCT domain is necessary for CPL4’s function. A suite of xenobiotic stress responsive genes shows constitutive up-regulation in CPL4 knockdown transgenic (CPL4RNAi) lines, indicating that CPL4 negatively regulates the toxic chemical detoxification pathway. The CPL4RNAi plants accumulate aberrant 3’-extended transcripts from many pol II-dependent small nuclear RNA (snRNA) loci. The snRNA 3’-extension gives rise to a snRNA transcript fused with a downstream protein-coding gene (DPG) if present. Such snRNA-DPG fusion transcripts can be found in other plant species. A short, unstable non-coding RNA produced from a protein-coding locus driven by a transposable-embedded snRNA promoter can yield the full-length product in the CPL4RNAi plants. These snRNA-DPGs can be induced in wild type by salt stress, which affects pol II-CTD phosphorylation status. These results indicate a potential stress-inducible conversion of non-coding RNA transcription into protein-coding transcription mediated by pol II-CTD phosphoregulation. CPL4RNAi root explants exhibit enhanced capability of de novo shoot organogenesis due to cytokinin hypersensitivity and earlier induction of shoot apical meristem regulatory genes. A potential involvement of an operon-like cluster of thalianol biosynthesis genes in the CPL4RNAi organogenesis phenotype is implicated. Taken together, Arabidopsis CPL4 is an essential pol II-CTD phosphatase, regulating stress-responsive and organogenesis pathways through protein-coding and non-coding RNA transcriptions

Preparation of a Series of Pyridyl Phenylureas of Potential Agricultural Interest

Substituted phenylurea derivatives of 3-amino-2-chloro-5-methylpyridine and 5-amino-2-chloro-3- methylpyridine were prepared by treating the amines with appropriately substituted phenyl isocyanates. Structure- confirming spectral data are also presented

TOLERANCE OF SEEDLING TURFGRASS SPECIES TO ALS INHIBITING HERBICIDES

Acetolactate synthase (ALS) inhibiting herbicides are commonly used to eliminate weeds from mature turfgrasses. Field trials were conducted from 2004-2006, testing ALS herbicides for preemergence and early postemergence activity on newly seeded turfgrasses, using four species: Riviera bermuda, Zenith and Companion zoysia, L- 93 creeping bentgrass, and Poa annua L. Data collected were phytotoxicity and percent turf cover. Bermuda and zoysia herbicides were metsulfuron-methyl (42 g ha-1), trifloxysulfuron (29 g ha-1), flazasulfuron (53 g ha-1), foramsulfuron (30 g ha-1), bispyribac-sodium (112 g ha-1), and rimsulfuron (35 g ha-1). Treatments occurred the day of seeding and two-three weeks after seeding. Flazasulfuron, trifloxysulfuron and bispyribac-sodium caused significant damage in all treatments. Data suggests that bermuda and zoysia are tolerant of seedling treatments of foramsulfuron, rimsulfuron, and metsulfuron-methyl at these rates. Bentgrass and P. annua herbicides were foramsulfuron (15 and 30 g ha-1), siduron (2803 g ha-1), bispyribac-sodium (49 g ha-1), and paclobutrazol (281 g ha-1). Treatments occurred the day of seeding, two and four weeks after seeding. Foramsulfuron at 15 and 30 g ha-1 caused significant damage regardless of when it was applied. Data suggests that bentgrass and P. annua are tolerant of seedling treatments of siduron, paclobutrazol, and bispyribac-sodium at these rates

W218 Trade Names of Herbicides Labeled for Use in Turf

Version 3.